NO20170057A1

NO20170057A1 - DEVICE FOR SENSING AND SEALING SENSOR ELEMENTS IN PRESSURE-WALLING WALL

Info

Publication number: NO20170057A1
Application number: NO20170057A
Authority: NO
Inventors: Espen Ekeland
Original assignee: Espen Ekeland
Priority date: 2017-01-15
Filing date: 2017-01-15
Publication date: 2018-07-16

Abstract

Innspennings- og tetningssystem for høye trykk og høye temperaturer der tetning og montasje blir pålitelig ved en metallisk tetning som forspennes via et korrosjonsbestandig kulelager.Clamping and sealing system for high pressure and high temperatures where sealing and mounting becomes reliable with a metallic seal which is pre-stressed via a corrosion resistant ball bearing.

Description

INNRETNING FOR INNSPENNING OG TETNING AV SENSORELEMENTER I TRYKKBÆRENDE VEGG DEVICE FOR TENSIONING AND SEALING SENSOR ELEMENTS IN PRESSURE-BEARING WALLS

Oppfinnelsens tekniske område Technical field of the invention

Foreliggende oppfinnelse vedrører en maskinteknisk metode og geometri for å gi inspenning og tetning av sensorelementer i en trykkbærende vegg, hovedsagligfor anvendelse i deteksjon av fluidnivå og –art i trykktanker i prosessutstyr. The present invention relates to a mechanical engineering method and geometry for clamping and sealing sensor elements in a pressure-bearing wall, mainly for use in detection of fluid level and type in pressure tanks in process equipment.

Bakgrunn for oppfinnelsen Background for the invention

Trykktett sammenføyning av maskindeler er et grunnelement i majoriteten av maskinkonstruksjoner, rørsystemer og prosessutstyr. Pressure-tight joining of machine parts is a basic element in the majority of machine structures, pipe systems and process equipment.

De første velykkede tetningskonstruksjoner i moderne forstand er av forholdsvis ny dato, de skriver seg fra senbarokken. Denis Papin fremstilte i modellformat i 1790en sylinder med tettsluttende stempel. Tetningselemenene var opprinnelig lær og tekstiler. En tetning for et bevegelig stempel eller roterende aksel betegnes gjerne som dynamiske tetninger. Det foreligger da en bevegelse mellom de to elementer som skal forsegles relativt til hverandre. Foranledningen til den utvikling som startet med dette var behovet for å omforme energien i vanndamp til mekanisk arbeid. Dette ledet frem til dampmaskiner. På samme tid og av samme beveggrunner trengtes tilførselsrør med tette forbindelser. Det ga opphav til rørskjøter der delene i hovedsak ikke beveges i forhold til hverandre. Denne kategori tetninger betegnes statiske tetninger. Den foreliggende oppfinnelse omhandler en underkategori av statiske tetninger for fluider. Væsker eller gasser vil i denne sammenheng betegnes fluider. The first successful sealing constructions in the modern sense are of relatively recent date, they date from the late Baroque. Denis Papin produced in model format in 1790 a cylinder with a tight-fitting piston. The sealing elements were originally leather and textiles. A seal for a moving piston or rotating shaft is often referred to as dynamic seals. There is then a movement between the two elements that are to be sealed relative to each other. The reason for the development that started with this was the need to transform the energy in water vapor into mechanical work. This led to steam engines. At the same time and for the same reasons, supply pipes with tight connections were needed. This gave rise to pipe joints where the parts essentially do not move in relation to each other. This category of seals is called static seals. The present invention deals with a subcategory of static seals for fluids. Liquids or gases will be referred to in this context as fluids.

Tetningselementene var opprinnelig lær, tekstiler,o.lign. Senere har polymere og eleastomere stoffer kommet i tillegg. De meget vellykkede og meget anvendte O-ringer er blant disse. The sealing elements were originally leather, textiles, etc. Later, polymeric and elastomeric substances have been added. The very successful and widely used O-rings are among these.

For visse anvendelser kommer imidlertid slike tetninger til kort. Det kan skyldes høy temperatur eller spesielle krav til tetthet eller styrke. Elastomere og polymere tetninger vil alltid slippe igjennom fluider i noen grad ved diffusjon. Tetninger der diffusjon er forhindret kan betegnes som molkylært tette. For certain applications, however, such seals fall short. This may be due to high temperature or special requirements for density or strength. Elastomeric and polymeric seals will always let fluids through to some extent by diffusion. Seals where diffusion is prevented can be described as molecularly tight.

I elektroniske måleinstrumeter for måling inne i prosessutstyr under drift, foreligger i alminnelighet krav om moekylær tetthet. Vanlig i slike anvendelser er også temperaturer der elastomere og polymere tetninger har reduserte egenskaper. In electronic measuring instruments for measuring inside process equipment during operation, there are generally requirements for molecular tightness. Temperatures where elastomeric and polymeric seals have reduced properties are also common in such applications.

Foreligende oppfinnelse vedrører en mekanisk utførelse som ved kompakte dimensjoner gir molkylær tetthet og ved friksjonsreduserende element gir høy forspenning og derved sikker forbindelse. Utførelsen har vist at den tåler repetert montasje og demontasje. Det er en vesentlig fordel også ved feilsøking og utbedring. The present invention relates to a mechanical design which, with compact dimensions, provides molecular density and, with a friction-reducing element, provides a high bias and thereby a secure connection. The design has shown that it can withstand repeated assembly and disassembly. It is also a significant advantage for troubleshooting and rectification.

Tidligere forsøk på å geometrier med oppfinnelsens hensikt mislyktes. Det er ikke plass til en boltsirkel uten at boltene blir så små at tiltrekkingen blir upålitelig ved de forspenningskrefter som kreves. En gjengering mot et flatt anlegg ga for stor friksjon. De vanlige lavfriksjons lagermaterialer har vist seg enten for ettergivende eller galvanisk ugunstige. Konvensjonelle kulelager i korrosjonsbestandige materialer er ikke kommersielt tilgjengelige. En metode for å få øket forspenningskraften ved å bruke en differensialgjenge, så som en ringmutter med en stigning på en gjenge på ringmutteren yttre sylinderflate og en mindre stgning på ringmutterns indre sylinderflate, viste seg upraktisk vanskelig å montere siden det element som skal forspennes og forsegles da må holdes fast for rotasjon under montasjen. Roatsjon i tetningsflatene forringer forseglingspåliteligheten til det uanvendelige. Dette skyldes blant annet at for en stor del anvendelser for oppfinnelsen, vil en flerhet av tetninger være forbundet med det volum inn til hvilket lekkasjer skal forhindres. Dermed må samtlige være tette for installasjonens funksjon ikke skal ødelegges. Dette stiller ekstra krav til tetningenes funksjonssikkerhet. Previous attempts to geometries with the purpose of the invention failed. There is no room for a bolt circle without the bolts being so small that the tightening becomes unreliable at the preload forces required. A threading against a flat surface produced too much friction. The usual low-friction bearing materials have proven either too compliant or galvanically unfavorable. Conventional ball bearings in corrosion-resistant materials are not commercially available. A method of increasing the pre-tensioning force by using a differential thread, such as a ring nut with a pitch of one thread on the outer cylinder surface of the ring nut and a smaller pitch on the inner cylinder surface of the ring nut, proved impractically difficult to assemble since the element to be pre-tensioned and sealed then must be held firmly for rotation during assembly. Rotation in the sealing surfaces impairs the sealing reliability of the unusable. This is due, among other things, to the fact that for a large number of applications for the invention, a plurality of seals will be connected to the volume into which leaks are to be prevented. Thus, all must be sealed so that the function of the installation is not destroyed. This places additional demands on the functional reliability of the seals.

Ved en anvendelse av oppfinnelsen inngår en kapasitiv sensor 5 som skal plasseres i en boring perpendikulært på aksen i et rørformet hus 6. Vanlig vil være en flerhet slike sensorer langs det rørformede huset slik at målinger kan gi en profil av karakter og spesifikk masse av omgivende fluid. Dette er illustert i Figur 1. An application of the invention includes a capacitive sensor 5 which is to be placed in a bore perpendicular to the axis in a tubular housing 6. Usually there will be a plurality of such sensors along the tubular housing so that measurements can provide a profile of the character and specific mass of the surrounding fluid. This is illustrated in Figure 1.

Oppfinnelsen betår i at et sensorelement 5 spennes inn i et rørformet hus med en ringmutter 2 og slik at tetning oppnås ved forspenning av en tetningingsring 1 mot koniske flater 9 og 10 i sensorelementet 5 og det rørformede hus 6. The invention consists in a sensor element 5 being clamped into a tubular housing with a ring nut 2 and so that sealing is achieved by biasing a sealing ring 1 against conical surfaces 9 and 10 in the sensor element 5 and the tubular housing 6.

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Claims

Summary of the invention

The present invention consists in exploiting the possibilities for space-saving and corrosion-resistant clamping and sealing of sensor elements using a finely threaded ring nut in combination with ball bearings with balls in high-performance ceramics and in combination with the design of metal-to-metal seals that allow multiple assembly and reassembly without replacement of parts.

Brief description of the drawings

Figure 1 shows how the main parts in a possible embodiment of the invention are arranged in a typical application.

Figure 2 shows a typical assembly of the main parts of the invention.

Figure 3 shows a typical assembly of the main parts of the invention made clear in a section.

Figure 4 shows a typical design of the sealing ring 1 in perspective, in sectional perspective and in orthogonal section..

Figure 5 shows a typical design of the ring nut 2 in perspective, in sectional perspective and in orthogonal section.. Figure 6 shows a typical design of the ball holder 3 with balls 4 in perspective.

Figure 7 shows a typical embodiment of a sensor element 5 in perspective and in sectional perspective.

Detailed description of the invention

Figure 3 shows a device according to the invention, characterized in that it consists of a threaded ring 2 - a ring nut - which is threaded into a tubular housing 6 with a fine thread 8. On a surface perpendicular to the axis of the ring nut 2, it is provided with a track 14 which is shaped as part of a toroidal surface. In this groove runs a set of balls 4 which are held at a uniform distance by a disc 3 with a row of holes on a dividing circle equal to the mean diameter of the toroidal groove. As this ball holder disc is made of a heat-resistant polymer material of the fluorocarbon type, the balls can be held firmly in the row of holes by a light press fit. Furthermore, the element 5 which is to be attached and sealed can be designed with a slightly conical part 10 so that the ball holder ring when first assembled in a corner of this 11 is deformed slightly radially outwards so that a profile is formed in the bores for the balls so that these are held permanently in ball retainer ring. This is advantageous during assembly. The deformation can advantageously be done against a dummy before the actual assembly. In a successful application of the invention, 25,056 bullets were used. A favorable but secondary feature of the invention advantageously solves the practical handling of such numbers.

The ring nut 2 is provided with a hole 12 for a spanner. These holes are placed so close to the cylindrical surface 13 in the ring that this is slightly deformed when the holes are drilled so that a retaining profile is formed for the ball retainer ring.

According to the invention, a conical surface 10 with a flank angle of approximately 15 deg is placed on a circumference of the element to be attached and sealed, i.e. a tip angle of 30 deg. The tip of this cone faces outward relative to the body of the element's main geometry. A sealing ring 1 with an internal conical surface which has a slightly smaller flank angle than the opposite conical surface is placed against this cone. This provides a facility on a narrow annular area so that high sealing pressure can be achieved with small biasing forces. The sealing ring 1 is designed with yet another conical surface 9 separated from the first and with conicity that opens the opposite way. The two conical surfaces would like to have approximately the same flank angle, but do not need to lie on the same diameter. This internal cone is brought into contact with an external cone 9 which is machined into the tubular housing 6 on the same axis as the thread 8 for the ring nut 2 and with a flank angle somewhat greater than the flank angle of the opposite cone in the sealing ring. In this way, high sealing pressure will again be achieved with small prestressing forces.

Ring nut 2 and sealing ring 1 can advantageously be coated with a softer material such as silver to reduce friction and risk of tearing or cold welding in threads and sealing surfaces.

According to the invention, corrosion-resistant ball storage can be achieved by using ceramic balls 4 of high-strength ceramics such as silicon nitride.

Pa ten tkra v

1. Device for achieving space-saving and corrosion-resistant clamping and sealing of a rotationally symmetrical machine part

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